Individualizing liver transplant immunosuppression using a phenotypic personalized medicine platform

The first human liver transplant operation was performed by Thomas Starzl in 1963. The next two decades were marked by difficulties with donor organ quality, recipient selection, operative and perioperative management, immunosuppression and infectious complications. Advances in each of these areas transformed liver transplantation from an experimental procedure to a standard treatment for end-stage liver disease and certain cancers. From the handful of pioneering programmes, liver transplantation has expanded to hundreds of programmes in >80 countries. 1-year patient survival rates have exceeded 80% and outcomes continue to improve. This success has created obstacles. Ongoing challenges of liver transplantation include those concerning donor organ shortages, recipients with more advanced disease at transplant, growing need for retransplantation, toxicities and adverse effects associated with long-term immunosuppression, obesity and NASH epidemics, HCV recurrence and the still inscrutable biology of hepatocellular carcinoma. This Perspectives summarizes this transformation over time and details some of the challenges ahead.

A mixture of drugs is often more effective than using a single effector. However, it is extremely challenging to identify potent drug combinations by trial and error because of the large number of possible combinations and the inherent complexity of the underlying biological network. With a closed-loop optimization modality, we experimentally demonstrate effective searching for potent drug combinations for controlling cellular functions through a large parametric space. Only tens of iterations out of one hundred thousand possible trials were needed to determine a potent combination of drugs for inhibiting vesicular stomatitis virus infection of NIH 3T3 fibroblasts. In addition, the drug combination reduced the required dosage by approximately 10-fold compared with individual drugs. In another example, a potent mixture was identified in thirty iterations out of a possible million combinations of six cytokines that regulate the activity of nuclear factor kappa B in 293T cells. The closed-loop optimization approach possesses the potential of being an effective approach for manipulating a wide class of biological systems.

A major challenge in stem cell-mediated regenerative medicine is the development of defined culture systems for the maintenance of clinical-grade human embryonic stem (hES) cells. Here, we identify, using a feedback system control scheme, a unique combination of three small molecule inhibitors that enables the maintenance of hES cells on a fibronectin-coated surface through single cell passaging. After 20 passages, the undifferentiated state of the hES cells was confirmed by OCT4, SSEA4 and NANOG expressions, whereas their pluripotent potential and genetic integrity were demonstrated by teratoma formation and normal karyotype, respectively. Our study attests to the power of the feedback system control scheme to quickly pinpoint optimal conditions for desired biological activities, and provides a chemically defined, scalable and single cell passaging culture system for hES cells.